Battery protecting apparatus and battery protecting circuit

Abstract

A battery protecting circuit is disclosed that includes a negative voltage terminal voltage detecting circuit that detects when a voltage of a negative voltage terminal decreases to less than a predetermined voltage; an abnormality detecting circuit that detects an abnormality in charge/discharge conditions of a battery; a switch that is connected between the battery and the negative voltage terminal, the switch being turned off when the negative voltage terminal voltage detecting circuit detects that the voltage of the negative voltage terminal has decreased to less than the predetermined voltage and when the abnormality detecting circuit detects the abnormality in the charge/discharge conditions of the battery; a delay time reducing circuit that reduces a time period from a time the abnormality in the charge/discharge conditions of the battery is detected to a time the switch is turned off when the voltage of the negative voltage terminal decreases to less than the predetermined voltage; and an output invalidating circuit that invalidates an output of the negative voltage terminal voltage detecting circuit.

1. A battery protecting circuit, comprising:
 a negative voltage terminal voltage detecting circuit that detects when a voltage of a negative voltage terminal decreases to less than a predetermined voltage; 
 an abnormality detecting circuit that detects an abnormality in charge/discharge conditions of a battery; 
 a switch that is connected between the battery and the negative voltage terminal, the switch being turned off when the negative voltage terminal voltage detecting circuit detects that the voltage of the negative voltage terminal has decreased to less than the predetermined voltage and when the abnormality detecting circuit detects the abnormality in the charge/discharge conditions of the battery; 
 a delay time reducing circuit that reduces a time period from a time the abnormality in the charge/discharge conditions of the battery is detected to a time the switch is turned off when the voltage of the negative voltage terminal decreases to less than the predetermined voltage; and 
 an output invalidating circuit that invalidates an output of the negative voltage terminal voltage detecting circuit during inspection, and that validates the output of the negative voltage terminal detecting circuit after the inspection, 
 wherein the negative voltage terminal voltage detecting circuit includes a comparator, and the output invalidating circuit is connected between an output of the comparator and ground without intervention of a switch. 
 
     
     
       2. The battery protecting circuit as claimed in  claim 1 , wherein
 the output invalidating circuit is connected between ground and the output of the negative voltage terminal voltage detecting circuit, and includes a fuse; and 
 the output of the negative voltage terminal voltage detecting circuit is validated by melting the fuse. 
 
     
     
       3. The battery protecting circuit as claimed in  claim 1 , wherein
 the negative voltage terminal voltage detecting circuit, the abnormality detecting circuit, and the output invalidating circuit are integrated in a single-chip. 
 
     
     
       4. The battery protecting circuit as claimed in  claim 1 , wherein the output invalidating circuit comprises a fuse. 
     
     
       5. The battery protecting circuit as claimed in  claim 1 , wherein the inspection is a period in which the operation of the abnormality detecting circuit is tested.